////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2011-2021 The Octave Project Developers
//
// See the file COPYRIGHT.md in the top-level directory of this
// distribution or <https://octave.org/copyright/>.
//
// This file is part of Octave.
//
// Octave is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Octave is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Octave; see the file COPYING.  If not, see
// <https://www.gnu.org/licenses/>.
//
////////////////////////////////////////////////////////////////////////

#if defined (HAVE_CONFIG_H)
#  include "config.h"
#endif

#include <QListWidget>
#include <QEvent>
#include <QMouseEvent>

#include "Container.h"
#include "ListBoxControl.h"
#include "QtHandlesUtils.h"

#include "octave-qobject.h"

namespace octave
{

  static void
  updateSelection (QListWidget *list, const Matrix& value)
  {
    octave_idx_type n = value.numel ();
    int lc = list->count ();

    list->clearSelection ();

    for (octave_idx_type i = 0; i < n; i++)
      {
        int idx = octave::math::round (value(i));

        if (1 <= idx && idx <= lc)
          {
            list->item (idx-1)->setSelected (true);
            list->scrollToItem (list->item (idx-1));
            if (i == 0
                && list->selectionMode () == QAbstractItemView::SingleSelection)
              break;
          }
        else
          {
            // Invalid selection.
            list->clearSelection ();
            break;
          }
      }
  }

  ListBoxControl*
  ListBoxControl::create (octave::base_qobject& oct_qobj,
                          octave::interpreter& interp,
                          const graphics_object& go)
  {
    Object *parent = parentObject (interp, go);

    if (parent)
      {
        Container *container = parent->innerContainer ();

        if (container)
          return new ListBoxControl (oct_qobj, interp, go,
                                     new QListWidget (container));
      }

    return nullptr;
  }

  ListBoxControl::ListBoxControl (octave::base_qobject& oct_qobj,
                                  octave::interpreter& interp,
                                  const graphics_object& go, QListWidget *list)
    : BaseControl (oct_qobj, interp, go, list), m_blockCallback (false),
      m_selectionChanged (false)
  {
    uicontrol::properties& up = properties<uicontrol> ();

    list->addItems (Utils::fromStringVector (up.get_string_vector ()));
    if ((up.get_max () - up.get_min ()) > 1)
      list->setSelectionMode (QAbstractItemView::ExtendedSelection);
    else
      list->setSelectionMode (QAbstractItemView::SingleSelection);
    Matrix value = up.get_value ().matrix_value ();
    if (value.numel () > 0)
      {
        octave_idx_type n = value.numel ();
        int lc = list->count ();

        for (octave_idx_type i = 0; i < n; i++)
          {
            int idx = octave::math::round (value(i));

            if (1 <= idx && idx <= lc)
              {
                list->item (idx-1)->setSelected (true);
                list->scrollToItem (list->item (idx-1));
                if (i == 0 && (list->selectionMode ()
                               == QAbstractItemView::SingleSelection))
                  break;
              }
          }
      }

    list->viewport ()->installEventFilter (this);

    connect (list, &QListWidget::itemSelectionChanged,
             this, &ListBoxControl::itemSelectionChanged);
    connect (list, &QListWidget::activated,
             this, &ListBoxControl::itemActivated);
    connect (list, &QListWidget::itemPressed,
             this, &ListBoxControl::itemPressed);
  }

  ListBoxControl::~ListBoxControl (void)
  { }

  void
  ListBoxControl::update (int pId)
  {
    uicontrol::properties& up = properties<uicontrol> ();
    QListWidget *list = qWidget<QListWidget> ();

    switch (pId)
      {
      case uicontrol::properties::ID_STRING:
        m_blockCallback = true;
        list->clear ();
        list->addItems (Utils::fromStringVector (up.get_string_vector ()));
        updateSelection (list, up.get_value ().matrix_value ());
        m_blockCallback = false;
        break;

      case uicontrol::properties::ID_MIN:
      case uicontrol::properties::ID_MAX:
        if ((up.get_max () - up.get_min ()) > 1)
          list->setSelectionMode (QAbstractItemView::ExtendedSelection);
        else
          list->setSelectionMode (QAbstractItemView::SingleSelection);
        break;

      case uicontrol::properties::ID_LISTBOXTOP:
        {
          int idx = octave::math::fix (up.get_listboxtop ());
          if (idx > 0)
            list->scrollToItem (list->item (idx-1),
                                QAbstractItemView::PositionAtTop);
          break;
        }

      case uicontrol::properties::ID_VALUE:
        m_blockCallback = true;
        updateSelection (list, up.get_value ().matrix_value ());
        m_blockCallback = false;
        break;

      default:
        BaseControl::update (pId);
        break;
      }
  }

  void
  ListBoxControl::sendSelectionChange ()
  {
    if (! m_blockCallback)
      {
        QListWidget *list = qWidget<QListWidget> ();

        QModelIndexList l = list->selectionModel ()->selectedIndexes ();
        Matrix value (dim_vector (1, l.size ()));
        int i = 0;

        for (const auto& idx : l)
          value(i++) = idx.row () + 1;

        emit gh_set_event (m_handle, "value", octave_value (value), false);
        emit gh_callback_event (m_handle, "callback");
      }

    m_selectionChanged = false;
  }

  void
  ListBoxControl::itemSelectionChanged (void)
  {
    if (! m_blockCallback)
      m_selectionChanged = true;
  }

  void
  ListBoxControl::itemActivated (const QModelIndex &)
  {
    m_selectionChanged = true;
  }
  void
  ListBoxControl::itemPressed (QListWidgetItem*)
  {
    m_selectionChanged = true;
  }

  bool
  ListBoxControl::eventFilter (QObject *watched, QEvent *e)
  {
    // listbox change
    if (watched == m_qobject)
      {
        switch (e->type ())
          {
          case QEvent::KeyRelease:
            if (m_selectionChanged)
              sendSelectionChange ();
            m_selectionChanged = false;
            break;

          default:
            break;
          }

        return Object::eventFilter (watched, e);
      }
    // listbox viewport
    else
      {
        bool override_return = false;
        QListWidget *list = qWidget<QListWidget> ();

        switch (e->type ())
          {
          case QEvent::MouseButtonPress:
            {
              QMouseEvent *m = dynamic_cast<QMouseEvent *> (e);

              if (m->button () & Qt::RightButton)
                override_return = true;
              else
                {
                  if (! list->indexAt (m->pos ()).isValid ())
                    override_return = true;
                  m_selectionChanged = true;
                }
              break;
            }
          case QEvent::MouseButtonRelease:
            {
              QMouseEvent *m = dynamic_cast<QMouseEvent *> (e);

              if (m->button () & Qt::RightButton)
                override_return = true;

              else if (! list->indexAt (m->pos ()).isValid ())
                {
                  list->setCurrentRow (list->count () - 1);
                  override_return = true;
                }

              if (m_selectionChanged)
                sendSelectionChange ();
              m_selectionChanged = false;

              break;
            }
          default:
            break;

          }
        return BaseControl::eventFilter (watched, e) || override_return;
      }
  }
}
